Heater Matrix problem?

[stevon]

Hi

I've got an old Focus 03 Reg.

So today I got in the car to be greeted with a damp smell, a puddle on the floor of the passenger side footwell and a gurgling noise coming from the passenger side when I put the heater on. 

Also terrible steaming up issues.

Did a quick google and all discussion seem to point to a leaking heater matrix? (if that's the right way to say it?).  Now it has been raining hard now for what feels like forever so I suppose there could be another explanation but I guess that's just clutching at straws.

So basically how serious of a problem is this?  Is this an expensive job? Anybody have the same issue and can offer an estimate cost of what's it's going to fix?

Also as I won't be able to get any work done for about a month at the earliest is it going to be a massive problem if I continue to drive in in the meantime? (Assuming I keep the coolant topped up and manage to actually see that is?)

Thanks, any advice firstly on whether this sounds like the real problem and also the other questions.

Thanks very much

Ste.